netdev - Re: [PATCH net-next v4 3/6] vhost/vsock: support MSG

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Date:   Fri, 3 Sep 2021 15:34:52 +0300
From:   Arseny Krasnov <arseny.krasnov@...persky.com>
To:     Stefano Garzarella <sgarzare@...hat.com>
CC:     Stefan Hajnoczi <stefanha@...hat.com>,
        "Michael S. Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Norbert Slusarek <nslusarek@....net>,
        Colin Ian King <colin.king@...onical.com>,
        Andra Paraschiv <andraprs@...zon.com>,
        "kvm@...r.kernel.org" <kvm@...r.kernel.org>,
        "virtualization@...ts.linux-foundation.org" 
        <virtualization@...ts.linux-foundation.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stsp2@...dex.ru" <stsp2@...dex.ru>,
        "oxffffaa@...il.com" <oxffffaa@...il.com>
Subject: Re: [PATCH net-next v4 3/6] vhost/vsock: support MSG_EOR bit
 processing


On 03.09.2021 15:14, Stefano Garzarella wrote:
> On Fri, Sep 03, 2021 at 08:55:39AM +0200, Stefano Garzarella wrote:
>> On Fri, Sep 03, 2021 at 09:15:38AM +0300, Arseny Krasnov wrote:
>>> 'MSG_EOR' handling has similar logic as 'MSG_EOM' - if bit present
>>> in packet's header, reset it to 0. Then restore it back if packet
>>> processing wasn't completed. Instead of bool variable for each
>>> flag, bit mask variable was added: it has logical OR of 'MSG_EOR'
>>> and 'MSG_EOM' if needed, to restore flags, this variable is ORed
>>> with flags field of packet.
>>>
>>> Signed-off-by: Arseny Krasnov <arseny.krasnov@...persky.com>
>>> ---
>>> drivers/vhost/vsock.c | 22 +++++++++++++---------
>>> 1 file changed, 13 insertions(+), 9 deletions(-)
>>>
>>> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
>>> index feaf650affbe..93e8d635e18f 100644
>>> --- a/drivers/vhost/vsock.c
>>> +++ b/drivers/vhost/vsock.c
>>> @@ -114,7 +114,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>>> 		size_t nbytes;
>>> 		size_t iov_len, payload_len;
>>> 		int head;
>>> -		bool restore_flag = false;
>>> +		u32 flags_to_restore = 0;
>>>
>>> 		spin_lock_bh(&vsock->send_pkt_list_lock);
>>> 		if (list_empty(&vsock->send_pkt_list)) {
>>> @@ -179,15 +179,20 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>>> 			 * created dynamically and are initialized with header
>>> 			 * of current packet(except length). But in case of
>>> 			 * SOCK_SEQPACKET, we also must clear message delimeter
>>> -			 * bit(VIRTIO_VSOCK_SEQ_EOM). Otherwise, instead of one
>>> -			 * packet with delimeter(which marks end of message),
>>> -			 * there will be sequence of packets with delimeter
>>> -			 * bit set. After initialized header will be copied to
>>> -			 * rx buffer, this bit will be restored.
>>> +			 * bit (VIRTIO_VSOCK_SEQ_EOM) and MSG_EOR bit
>>> +			 * (VIRTIO_VSOCK_SEQ_EOR) if set. Otherwise,
>>> +			 * there will be sequence of packets with these
>>> +			 * bits set. After initialized header will be copied to
>>> +			 * rx buffer, these required bits will be restored.
>>> 			 */
>>> 			if (le32_to_cpu(pkt->hdr.flags) & VIRTIO_VSOCK_SEQ_EOM) {
>>> 				pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
>>> -				restore_flag = true;
>>> +				flags_to_restore |= VIRTIO_VSOCK_SEQ_EOM;
>>> +
>>> +				if (le32_to_cpu(pkt->hdr.flags & VIRTIO_VSOCK_SEQ_EOR)) {
>                                                                ^
> Ooops, le32_to_cpu() should close before bitwise and operator.
> I missed this, but kernel test robot discovered :-)
Sorry ><
>
>>> +					pkt->hdr.flags &= ~cpu_to_le32(VIRTIO_VSOCK_SEQ_EOR);
>>> +					flags_to_restore |= VIRTIO_VSOCK_SEQ_EOR;
>>> +				}
>>> 			}
>>> 		}
>>>
>>> @@ -224,8 +229,7 @@ vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
>>> 		 * to send it with the next available buffer.
>>> 		 */
>>> 		if (pkt->off < pkt->len) {
>>> -			if (restore_flag)
>>> -				pkt->hdr.flags |= cpu_to_le32(VIRTIO_VSOCK_SEQ_EOM);
>>> +			pkt->hdr.flags |= cpu_to_le32(flags_to_restore);
>>>
>>> 			/* We are queueing the same virtio_vsock_pkt to handle
>>> 			 * the remaining bytes, and we want to deliver it
>>> -- 2.25.1
>>>
>> Reviewed-by: Stefano Garzarella <sgarzare@...hat.com>
> NACK
>
> Please resend fixing the issue.
Done, v5 is sent
>
> Stefano
>
>